1. Field of the Invention
The present invention relates to an ink jet recording apparatus, and particularly to an ink jet recording apparatus provided with a function of suppressing curl generated in a recording medium after image formation.
2. Related Background Art
Recently, the ink jet recording apparatus is rapidly becoming widespread because of merits such as high image quality and low running cost. In a sheet material that is of the recording medium, not only plain paper but also dedicated paper for obtaining a photograph or a print having the same image quality as a printing technology is generally used. However, when the high-quality image is obtained by the ink jet technology, since solid printing is performed on the substantially whole surface of the sheet material, the ink discharge amount is remarkably increased, which results in problems such as cockling and curl.The cockling is a phenomenon in which the print is undulated after the image formation, and the curl is a phenomenon in which the print curls up. Particularly, in the high-speed printing or both-side printing, the generation of the curl becomes remarkable. Conventionally there is a method of suppressing the generation of the curl by adding a curl inhibitor into the ink to increase a viscosity of ink (for example, see Japanese Patent Application Laid-Open Nos. 2004-217930 and H09-176538).
According to the study results of the present inventors, the increase in viscosity of the ink by the addition of the curl inhibitor causes ink clogging to be generated in a discharge nozzle. When the ink having the high viscosity is used, ink jet discharge performance is decreased to lower the image quality after the image formation, and it is confirmed that apparatus performance and reliability are lost.